The letter did not disclose whether a new managing director of investments would be named.

The management change comes as the value manager has seen a major decline in assets under management over the last several years due to market losses and client terminations. The San Diego-based firm says it had $29.6 billion worth of assets of as Sept. 30, significantly below its 2007 pre-financial crisis assets of more than $100 billion.

The client letter does not directly address the reasons for the change. However, in a statement, Brandes spokeswoman Leah Brock said, “As a disciplined value investor focused on the long term, we do not base our decisions on short-term market trends. Consistent with that view, the succession planning and other changes we are undertaking over the next few months are part of a thoughtful and well-planned process to not only ensure continuity, but also promote talent and refine our structure to better serve clients.”

The client letter said: “Glenn has been in a leadership role at Brandes for over 25 years and has recently decided, for personal and professional reasons, that it is time to announce his decision to step aside as CEO early next year.” It added that Mr. Carlson will continue to be a senior partner and a member of the investment oversight committee.

The letter also said Mr. Carlson will “rotate” out of the firm’s large-cap investment committee, Brandes’ largest investment strategy.

The letter goes on to say that the large-cap committee will be split into two on Feb. 1. The committees will increase the focus on each large-cap investment product and include both new and existing members, the letter said.